1. Technical Field
The present invention generally relates to a method for cleaning deposits from an engine fuel delivery system such as a fuel injector.
2. Description of the Related Art
It is well known that automobile engines tend to form deposits on the surface of engine components, such as carburetor ports, throttle bodies, fuel injectors, intake ports, intake valves, and combustion chambers, due to the oxidation and polymerization of hydrocarbon fuel. These deposits, even when present in relatively minor amounts, often cause noticeable driveability problems, such as stalling and poor acceleration. Moreover, engine deposits can significantly increase an automobile's fuel consumption and production of exhaust pollutants. Therefore, the development of effective fuel detergents or “deposit control” additives to prevent or control such deposits is of considerable importance and numerous such materials are known in the art. However, even after employing fuel detergents, injectors and other components subject to heavy deposits and/or tenacious deposit regimes require occasional additional cleaning to maintain optimum performance.
Engines operating on diesel fuel rely on injection of diesel fuel into the combustion chamber of the engine rather than on aspiration of the fuel into the air intake system of the engine such as is the case with most gasoline engines. Diesel fuel injectors atomize the diesel fuel into very small droplets by forcing the fuel through a small injector hole or orifice under high pressure. In recent years, droplet size has been decreased by atomizing the fuel at higher pressures through smaller orifices, which are supplied through other injector parts of similarly smaller size such as pintles, armatures, plungers and needles, injector cups, and injection chambers. In addition many injectors are operating at higher temperatures than was previously the case. This is due not only to the increase in pressure, but also to changes in injector component designs, along with increased use of turbocharging, High Pressure Common Rail fuel systems (HPCR), fuel injection strategies, exhaust emissions and other efforts to control NVH (Noise, Vibration, and Harshness).
There have also been changes in recent years to the diesel fuel itself. The drastic reduction in the sulfur content of diesel fuel has made the fuel more oxidatively unstable, and in some cases requires higher amounts of fuel lubricity additives. Some states are also mandating the use of biodiesel which further complicates the problem.
These increased pressures and temperatures, and changes in the fuel, have resulted in increased amounts and increased sensitivity to deposits that form in the fuel injector and other fuel system components. These deposits stick or disable proper function of internal fuel system function, thus effecting the proper operation of the engines fuel system. Example of components that affected can include, but are not limited to, pintles, armatures, plungers and needles, injector cup, injection chamber intensifier piston, timing and fuel control circuits or valves. It has been found that the problems often are not evidenced until the injectors or fuel system components have been in use in the field for some time. Attempts to clean the sticking, stuck or clogged injectors using methods taught in the prior art have to date not been totally successful. Such attempts to fix this problem have been documented in, e.g., SAE papers-2008-01-0926, 2010-01-2242, 2010-01-2243, and 2010-01-2250.
It is also believed that the nature of the deposits has changed. SAE 2008-01-0926, “Investigation into the Formation and Prevention of Internal diesel Fuel Injector Deposits, and Fuels Technische Akademie Esslingen Colloquium 2009, “Effects of Fuel Impurities and Additive Interactions on the Formation of Internal Diesel Injector Deposits”, disclose that deposits in modern diesel fuel injector systems are of two different types: “polymeric” deposits derived from additives, especially polymeric succinimides, contained in the fuel; and sodium compounds.
U.S. Pat. No. 6,616,776 (“the '776 patent”) discloses a method for removing engine deposits in a reciprocating internal combustion engine by introducing a cleaning composition into an air-intake manifold of a warmed-up and idling reciprocating internal combustion engine and running the engine while the cleaning composition is being introduced. The '776 patent further discloses that the cleaning solution for use in the method contains a first solution containing a mixture of (a) a phenoxy mono- or poly(oxyalkylene) alcohol; (b) at least one solvent selected from (1) an alkoxy mono- or poly(oxyalkylene) alcohol and (2) an aliphatic or aromatic organic solvent; and (c) at least one nitrogen-containing detergent additive; and a second solution containing a mixture of: (d) a phenoxy mono- or poly(oxyalkylene) alcohol; (e) a cyclic carbonate; and (e) water.
U.S. Pat. No. 6,652,667 (“the '667 patent”) discloses a method for removing engine deposits in a gasoline internal combustion engine by introducing a cleaning composition into an air-intake manifold of a warmed-up and idling gasoline internal combustion engine and running the engine while the cleaning composition is being introduced. The '667 patent further discloses that the cleaning solution for use in the method contains (a) a phenoxy mono- or poly(oxyalkylene) alcohol; (b) at least one solvent selected from (1) an alkoxy mono- or poly(oxyalkylene) alcohol and (2) an aliphatic or aromatic organic solvent; and (c) at least one nitrogen-containing detergent additive.
U.S. Patent Application Publication No. 20050268540 (“the '540 application”) discloses a fuel composition for the control and/or removal of persistent engine deposits. The fuel composition disclosed in the '540 application contains a major amount of hydrocarbons boiling in the gasoline range fuel, a hydrocarbyl-substituted polyoxyalkylene amine and a glycol ether component.
U.S. Patent Application Publication No. 20100139697 (“the '697 application”) discloses a method for removing deposits from at least one compressor powered by an engine. The '697 application further discloses that the method involves (a) disconnecting, while the engine is turned off, a high pressure downstream side of said compressor from an intercooler, or an air intake manifold for non-intercooled engines, while leaving the compressor attached to a means used in the engine to drive the compressor, (b) diverting the output airflow from the compressor away from the engine to a disposal or to a means of separating a cleaning-fluid from air, (c) starting the engine, (d) introducing a means to inject said cleaning fluid into an air stream in the low pressure side upstream of the compressor; and (e) while the engine is running, injecting the cleaning fluid via the means in step (d) for a sufficient time to clean the compressor. The cleaning solution disclosed in the '697 application contains a major amount of an aromatic hydrocarbon solvent and at least one nitrogen containing detergent additive.
Accordingly, it would be desirable to develop methods for cleaning deposits from an engine fuel delivery system such as a fuel injector.